title: Qa-2, H-2K, and H-2D alloantigens evolved from a common ancestral gene.
abstract: The Tla region located on the murine 17th chromosome controls several serologically defined cell surface antigens. These antigens, referred to as Qa-1-5 and TL, are expressed on a variety of hematopoeitic cell populations. In the present studies we have immunoprecipitated isotopically labeled Qa-2 and H-2 molecules from mitogen-stimulated B6 spleen cells. Sequential immunoprecipitation experiments have shown that the determinants recognized by alpha Qa-2, alpha H-2Kb, and alpha H-2Db alloantisera reside on separate molecular species. Comparative mapping of the arginine-labeled tryptic peptides from Qa-2, H-2Kb, and H-2Db molecules indicate that Qa-2 is structurally distinct but that there is considerable structural homology; 21-43% of the Qa-2 peptides co-chromatograph with peptides derived from H-2Db and H-2Kb, respectively. Similar levels of homology are observed when Qa-2 is compared with H-2Kk or H-2Dd. The results show that the Qa-2 alloantigen is encoded by a locus separate from the loci encoding H-2K or H-2D alloantigens, but that the Qa-2, H-2K, and H-2D alloantigens are sufficiently related at the primary structural level to indicate that they evolved from a common primordial gene.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000032:analysis; D005802:Genes, MHC Class II; D006183:H-2 Antigens / Q000032:analysis*; D007519:Isoantigens / Q000032:analysis* / Q000235:genetics / Q000302:isolation & purification; D008239:Lysine / Q000032:analysis; D051379:Mice; D014357:Trypsin
chemical_list: D006183:H-2 Antigens; D007519:Isoantigens; D001120:Arginine; D014357:Trypsin; D008239:Lysine